DESCRIPTION (Applicant's Abstract): This application is a request for a Senior Scientist Award. The proposed research involves further development and expansion of 2 major projects in which the PI has been involved for many years (since 1979 on one, and since 1985 on the other). The first project is a longitudinal study of cigarette smoking. This is the longest and most comprehensive study of changes in smoking status that has been conducted. The current proposal carries this work forward and has several specific aims. The first set of studies will assess developmental trends in health-relevant cognitions and will assess the contributions of adult role acquisition and perceived control. Second, the natural history of smoking will be described within a developmental perspective, as both antecedents and consequences of smoking transitions are assessed. Third, we are now able to look at a second generation of participants and to investigate parental socialization of smoking and the intergenerational transmission of smoking. Finally, we shall adopt implicit measures of attitudes toward smoking and observe their role in smoking behavior and in parental socialization practices. The second project concerns the cognitive processes underlying the perceptions of individuals and groups. A conceptualization is provided, and differences between individuals and groups, as well as between different types of groups, are proposed. Central importance is given to the concept of entitativity, the perception that a number of individuals are joined together as a social unit. Differences in perceived entitativity are postulated to underlie differences in how information about group targets is processed. The specific studies will examine the antecedents and consequences of entitativity, and will explore the role of entitativity in stereotyping and ingroup/outgroup differentiation. Included in the methdological approaches will be laboratory studies, natural setting research, longitudinal studies, and a test of a comprehensive model of the mediating role of entitativity in the perception of different types of groups.